Effect of platelet-rich plasma on tendon-to-bone healing after rotator cuff repair in rats: an in vivo experimental study

Objective: The purpose of this experimental study was to analyze the effects of local autologous platelet-rich plasma (PRP) injection on tendon-to-bone healing in a rotator cuff repair model in rats.Methods: Rotator cuff injury was created in 68 left shoulders of rats. PRP was obtained from the blood of an additional 15 rats. The 68 rats were divided into 4 groups with 17 rats in each group; PRP group (Week 2), control group (Week 2), PRP group (Week 4), and control group (Week 4). Platelet-rich plasma or saline was injected to the repair area intraoperatively. Rats were sacrificed 2 and 4 weeks after the surgery. Histological analysis using a semiquantitative scoring was performed on 7 rats per group. Tendon integrity and increases in vascularity and inflammatory cells and the degree of new bone formation were evaluated and compared between the groups. The remaining tendons (n=10) were mechanically tested.Results: Degree of inflammation and vascularity were less in the study group at both time intervals (p 0.05). Tendon continuity was better in the study group at 2 weeks (p 0.05). Obvious new bone formation was detected in the control group at 4 weeks (p 0.05). Biomechanically, platelet-rich plasma-treated specimens were stronger at 2 weeks (p 0.05).Conclusion: Local autologous PRP injection may have beneficial effects on initial rotator cuff tendon-to-bone healing and enhance initial tendon-to-bone healing remodeling. This may represent a clinically important improvement in rotator cuff repair.